Disimulao' is a colloquial, shortened form of "disimulado," meaning "disguised" or "pretending not to notice." It perfectly captures the song's theme of trying to hide one's feelings.
The singer repeatedly uses this word to describe his attempts to act cool and unaffected, even though he's deeply in love. It's an engaging word because it's central to the narrative and reflects a common human experience of trying to play it cool.
Alizzz's "Disimulao" is such a fun, relatable look at trying (and failing!) to hide your feelings when you're totally smitten. Our singer is absolutely head over heels, but he's trying so hard to play it cool. He sings, "Me gusta hacerme tanto el disimulao' / Pa' que no se me note que me he enamorao'" [I like to play it so nonchalant / So it doesn't show that I've fallen in love]. He's doing everything he can to avoid showing it, like crossing the street or pretending not to see her when she throws him a kiss.
But let's be real, his attempts are pretty hilarious and over-the-top! He admits, "Fingí mi secuestro, mi muerte y un robo" [I faked my kidnapping, my death and a robbery] just to get out of something, and he's secretly looking at her photos. He even says, "¿No ves que cuando miras pongo cara de tonto?" [Don't you see that when you look, I make a silly face?]. It's clear by the end that all his efforts are useless because, as he puts it, "Te quiero y no lo sé disimular" [I love you and I don't know how to hide it]. It's a sweet, funny take on that universal feeling of being so in love you just can't keep it a secret anymore.